Abstract
The δ15N composition of the dominant form of dissolved inorganic nitrogen (DIN) was determined in upland groundwater, riparian groundwater, and stream water of the Barro Branco catchment, Amazônas, Brazil. The δ15N composition of organic nitrogen in riparian and upland leaf litter was also determined. The data for these waters could be divided into three groups: upland groundwater DIN predominately composed of NO3 − with δ15N values averaging 6.25 ± 0.9 riparian groundwater DIN primarily composed of NH4 + with δ15N values averaging 9.17 ± 1.0 and stream water DIN predominately composed of NO3 − with δ15N values averaging 4.52 ± 0.8‰ Nitrate samples taken from the stream source and from the stream adjacent to the groundwater transects showed a downstream increase in δ15N from 1.0to 4.5‰ Leaf litter samples averaged 3.5 ± 1.2‰
The observed patterns in isotopic composition, together with previously observed inorganic nitrogen species and concentration shifts between upland, riparian and stream waters, suggest that groundwater DIN is not the primary source of DIN to the stream. Instead, the isotopic data suggest that remineralization of organic nitrogen within the stream itself may be a major source of stream DIN, and that the majority of DIN entering the stream via groundwater flowpaths is removed at the riparian-stream interface.
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References
Bowden WB, McDowell WH, Asbury CE & Finley AM (1992) Riparian nitrogen dynamics in two geomorphologically distinct tropical rain forest watersheads: nitrous oxide fluxes. Biogeochemistry 18: 77–99
Brandes JA, Lambourne LD & Devol AH (1994) Changes in isotopic composition of nitrogen, oxygen, nitrate and ammonium duringin situ benthic flux chamber incubations. EOS 75: 127
Cline JD & Kaplan IR (1975) Isotopic fractionation of dissolved nitrate during denitrification in the eastern tropical North Pacific. Mar. Chem. 3: 271–299
Correa EF & Germon JC (1991) Dissimilative nitrate reduction to ammonium in different soils in waterlogged conditions. In: Berthelin J (Ed) Diversity of Environmental Biogeochemistry (pp 295–308). Elsevier, Amsterdam
Franken M, Irmler U & Klinge H (1979) Litterfall in inundation, riverine, and terra firme forests of Central Amazonia. Tropical Ecol. 20: 225–235
Haycock NE, Pinay G & Walker C (1993) Nitrogen retention in river corridors: European perspective. Ambio 22: 340–346
Henderson PA & Walker I (1986) On the leaf litter community of the Amazonian blackwater stream Tarumazinho. J. Tropical Ecol. 2: 1–17
Hübner H (1986) Isotope effects of nitrogen in the soil and biosphere. In: Fritz P & Fontes JC (Ed) Handbook of Environmental Isotope Geochemistry (pp 361–425). Elsevier, Amsterdam
Kendall C, Campbell DH, Burnas DA, Shanley JB, Silva SR & Chang CCY (1995) Tracing sources of nitrate in snowment runoff using the oxygen and nitrogen isotopic compositions of nitrate. Biogeochem. of Seas. Snow-Covered Catch. IAHS Publ. No. 228, pp 339–347
Kreitler CW & Browning LA (1983) Nitrogen-isotope analysis of groundwater nitrate in carbonate aquifers: natural sources vs. human pollution. J. Hydrol. 61: 285–301
Koroleff F (1969) Direct determination of ammonia as indophenol blue. Int. Cons. Explor. Mer. C.M
Létolle R (1980) Nitrogen-15 in the natural environment. In: Fritz P & Fontes JC (Ed) Handbook of Environmental Isotope Geochemistry (pp 407–433). Elsevier, Amsterdam
Mariotti A, Germon JC & Petal H (1981) Experimental determination of nitrogen kinetic isotope fractionations: some principles; illustration for denitrification and nitrification processes. Plant and Soil 62: 413–430
Mariotti A, Mariotti F, Champigny M-L, Amarger N & Moyse A (1982) Nitrogen isotope fractionation associated with nitrate reductase activity and uptake of NO3 by pearl millet. Plant Physiol. 69: 880–884
McClain ME, Richey JE & Pimentel TP (1994) Groundwater nitrogen dynamics at the terrestrial-lotic interface of a small catchment in the Central Amazon basin. Biogeochemistry 27: 113–127
McDowell WH, Bowden WB & Asbury CE (1992) Riparian nitrogen dynamics in two geomorphologically distinct tropical rain forest watersheds: subsurface solute patterns. Biogeochemistry 18: 53–75
Nadelhoffer KJ & Fry B (1994) Nitrogen isotope studies in forest ecosystems. In: Lajtha K & Michener RH (Ed) Stable Isotopes in Ecology and Environmental Science (pp 22–44). Blackwell Scientific Publications, Boston
Nortcliff S & Thornes JB (1988) The dynamics of a tropical floodplain environment with reference to forest ecology. J. Biogeogr. 15: 49–59
Stark N & Holley C (1975) Final report on studies of nutrient cycling on white and black water areas of Amazonia. Acta Amazonica 5: 51–76
Strickland JD & Parsons TR (1972) A Practical Handbook of Seawater Analysis. Bulletin Fisheries Research Board of Canada 167
Tiedje JM, Sorensen J & Chang YYL (1981) Assimilatory and dissimilatory nitrate reduction: perspectives and methodology for simultaneous measurement of several nitrogen cycle processes. In: Clark F & Rosswall T (Ed) Terrestrial Nitrogen Cycles (pp 331–342). Ecological Bulletin 33, Stockholm
Triska FJ & BM Buckley (1978) Patterns of nitrogen uptake and loss in relation to litter disappearance and associated invertebrate biomass in six streams of the Pacific Northwest, U.S.A. Verh. Internat. Verein. Limnol. 20: 1324–1332
Triska FJ, Duff JH & Avanzino RJ (1993) The role of water exchange between a stream channel and its hyporheic zone in nitrogen cycling at the terrestrial-aquatic interface. Hydrobiologia 251: 167–184
Velinsky DJ, Pennock JR, Sharp JH, Cifuentes LA & ML Fogel (1989) Determination of the isotopic composition of ammonium-nitrogen at the natural abundance level from estuarine waters. Mar. Chem. 26: 351–361
Wassenaar LI (1995) Evaluation of the origin and fate of nitrate in the Abbotsford aquifer using the isotopes of15N and18O in NO3 −. Appl. Geochem. 10: 391–405
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Brandes, J.A., McClain, M.E. & Pimentel, T.P. 15N evidence for the origin and cycling of inorganic nitrogen in a small Amazonian catchment. Biogeochemistry 34, 45–56 (1996). https://doi.org/10.1007/BF02182954
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DOI: https://doi.org/10.1007/BF02182954